Water-Heater T&P Relief and Discharge
Checks a water heater's T&P valve against its input and sizes the discharge pipe.
Example
You enter
- Heater input rating (BTU/hr) 50000
- T&P valve marked relief capacity (BTU/hr) 150000
- Valve discharge-outlet size 0.75
You get
- Minimum discharge pipe 0.75
- Rating margin (Btu/h) 100000
Details, formula, and sources
Checks the T&P relief valve's rating against the heater input and reports the IPC 504.6 discharge-pipe size and requirements.
rating_ok = valve_rating >= heater_input; discharge_in = valve outlet (never reduced). Output is a pass/fail and the IPC 504.6 discharge checklist, not a continuous quantity.
IPC 2021 Section 504 (504.4 valve rating vs heater input, 504.6 discharge piping) and ANSI Z21.22 / CSA 4.4 by name; first-principles comparison.
IPC 2021 free read-only at codes.iccsafe.org. The discharge requirements are public code text.
Estimate. AHJ and licensed professional govern.
Field names used by the API: heater_input, valve_rating, outlet_size, discharge_in, rating_margin_btuh
- Discharge size the full valve outlet (typ. 3/4 in), never reducedIPC 2021 Section 504.6
- Rating rule valve marked relief capacity >= heater input ratingIPC 2021 Section 504.4 / ANSI Z21.22